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How do one day simulator courses work?
There are companies such as this that offer one day full simulator experiences where you take several attempts at landing a 747 or something similar. Some people report success after a couple of attempts.
In this question, asked recently here on ASE, it was generally agreed upon that no-one could land such an aircraft without many hundreds of hours of training.
So how do these day-courses/experiences work? Do they somehow 'dumb down' the simulator, automating most or all of the process'?
Side-note: I am asking, because I am interested in learning the basics of flying, but could only afford simulator training, the actual school in my real country offers block bookings for a reasonable price.

@unnamed_Player I want to be prepared in case of pilot incapacitatation while I am a passenger on a commercial flight.

Some people consider it fun to play in a simulator for a few hours. They may not intend to ever get a pilot's license.

You really ought to take a nervous flyer course (for example, https://fearlessflyer.easyjet.com). You'll learn what goes on in the cockpit, but focused at what a passenger would experience. Any other preparation like this is a waste of time and money, unless you're an enthusiast who enjoys to try out a simulator.

That simulator experience looks like king-hell fun. And definitely worth the price.

You should look into buying a game like FSX or X-Plane. The payware addons have realistic autopilots which will help you with your fantasy

The simulators you are talking about simulate real life scenarios which can help you practice real life scenarios ... in a simulator. For an hour, they can teach you to land an airliner in nearly perfect weather conditions ... in a simulator. So, after spending some time there, you may be able to land the airplane ... in a simulator. Hence, none of this happens in real life.
Since your motives are very well known here, and asking an extremely hypothetical scenario in different words will not get you an answer of "yes Cloud, you can land an airplane", I'll be honest and sympathetic.
If you really want to be useful in an emergency which has only happened in your imagination, here is the plan of action for you:

get a private pilot license
get an instrument rating
get a commercial license
get an airline transport pilot license
have at least 2000 hours of general flying experience
get the rating for the type of aircraft for which you booked your next flight
hope that the situation of your imagination will actually happen
and lastly, hope that you will not be incapacitated before the pilots

So how much money would that checklist cost? And if one was to go through all of that effort... they might as well get a job as a commercial pilot while they're at it! :D

@Cloud - I think that's sort of the point!

You can get a type rating with just Private Pilot, IR and MEL.

I’ve done one of these before (not with that company). It literally used the Microsoft FSX game engine but with an A320 cockpit. You have an instructor guiding you and I got to fly around my local airport, land at Kai Tak at night (nailed my first attempt), and because I was in real-world training at the time I shot an ILS approach in zero visibility (definitely did not nail that one).
These simulators are usually aimed at people with little to no piloting experience who want some fun (and they are, I enjoyed mine and my dad has done it 3 or 4 times). If you’ve used FSX you know that you can adjust the realism settings to make it easier to fly so, with help from the instructor a novice can probably land it. At the very least you will learn about basic procedures, flaps etc, and what the cockpit looks like.
It will definitely not make you ready to land the real thing though. These things are designed for fun, not realism.

So how do these day-courses/experiences work? Do they somehow 'dumb
  down' the simulator, automating most or all of the process'?

Yes. They 'dumb down' your experience in two ways:

In the rear of the simulator there is a seat and a console, in real life an examiner sits there when evaluating pilots. But during your experience, there will be someone less senior sitting there. He/she will "dial-in" various parameters to make your life simple (e.g. choose an "easy" airfield, make the weather conditions "perfect" etc.).
Typically they will roll out an off-duty pilot who will sit next to you in the right hand seat. You will not notice it because you will be too busy with everything else that will be going on, but they will be sitting there acting as your second pair of hands.  They will have a hand on the stick "guiding" you, they will have feet on the rudder pedals so you don't need to worry about that, they willl have hand on the throttle so you don't need to worry about that.  Same goes for flaps and other knobs and switches ... they will either do it for you or they will give you orders (tell you exactly what to at the point when it needs to be done).

All in all, its a fun experience.  But don't kid yourself that you could be like in a movie and land a plane after only 40 minutes in the sim !
You can try asking for favours, but typically they will be reluctant to waste time dialing in trickier conditions or going hands-off if you have not demonstrated to them in the first five minutes that you can do a good job on your first attempt of landing in perfect conditions with zero hand-holding from the person in the right hand seat.
There is an old saying.  Any monkey can fly a plane, but only a pilot can land one.


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How exactly can an airship lose lift?
On this wiki page (under 'Comparison with heavier-than-air aircraft'), the altitude record of the L-55 Airship states:

The ultimate altitude record for a rigid airship was set in 1917 by the L-55 under the command of Hans-Kurt Flemming when he forced the airship to 7,300 m (24,000 ft) attempting to cross France after the "Silent Raid" on London. The L-55 lost lift during the descent to lower altitudes over Germany and crashed due to loss of lift.

I understand that lift on an airship is created through internal heated air and/or gases, rather than by the movement of air over a wing.
So, how exactly can an airship lose lift? (And how does altitude affect this?)

L-55 was LZ-101 in the numbering scheme used by Luftschiffbau Zeppelin. The run of airships from LZ-100 to LZ-103 were designed for 7300 m altitude - their gas bags were only ⅓ full at sea level! LZ-104 was even designed for 8000 m …

One solution to your question title:  Pop it with a pin...

The reason is a temperature difference between the lift gas and the surrounding air, and probably water uptake by the hull when descending through clouds.
A given mass of hydrogen will create a constant lift force, regardless of pressure or altitude, when at equal pressure and temperature with the surrounding air. Therefore, a change in altitude will not change the lift a rigid airship creates. Ideally.
However, air gets colder the higher you climb. The sun heats the atmosphere from below, by way of heating the ground, and space cools it from the top. Therefore, on many days the temperature gradient is bigger than its adiabatic value - that is the way thermals work! L-55 stayed at altitudes where air is -32°C according to the Standard Atmosphere. When descending, the surrounding air got warmer and also warmed up the lift gas, but only slowly. This means that, depending on the rate of descent, the lift gas lagged behind in temperature relative to the air, and this temperature difference reduced its lift capacity.
Note that adiabatic heating will already heat a gas when being compressed. The lapse rate of the atmosphere must be above the dry adiabatic value for this mechanism to work, which it is on many days. Especially behind a cold front. Note that L-55 encountered strong winds - just what you find in and behind a cold front. So it is safe to conclude that L-55 flew in labile air, and when it descended, that motion became unstable, at least close to the ground.
Kapitän Flemming simply descended too quickly. Slowing things down would have warmed the lift gas more, and less lift would have been lost. But delaying the descent has dangers of its own: The gas bags back then were made from goldbeater skin and had a certain amount of seepage. To compensate, Zeppelins started their trips with several tons of ballast water onboard, which was progressively dropped during the many hours of a normal trip. Taking a detour over France delayed the trip, so he was running short on time.
Normally, a loss of lift can be compensated by dynamic lift. With some angle of attack, an airship can create up to 20% of its weight in dynamic lift - as long as all engines are running. L-55 was blown south during the night after attacking Hull and Birmingham, and found itself far more south than assumed when dawn allowed the crew to get a ground fix. When back over Germany, L-55 ran out of fuel and dynamic lift was no longer available to compensate for the lower lift gas temperature. It made a rough landing in the Thuringian countryside near Tiefenort and had to be written off.
Literature: Heinz Urban, Zeppeline der kaiserlichen Marine 1914 bis 1918

I just thought that the temperature of the gas will decrease on ascent due to approximately isentropic expansion, and vv on descent. If I am right in guessing that this is (almost) the same for H2 and air, the gas temperature/height profile will lie between the dry adiabatic lapse rate and the actual lapse rate. If these assumptions are correct, and the airship starts down with the gas at the same temperature as the surrounding air, will it not reach the ground at least as warm as the air there, on account of compression, given the actual lapse rate is never > adiabatic? On the other hand...

...a descent in the morning would be during the time when the lower atmosphere is being heated by the sun. I need to learn more about how the diurnal thermal cycle varies with altitude...

@sdenham: How do thermals work? On many days the lapse rate is above its stable value, so adiabatic warming will not compensate for what is really happening on the way down. October 20, 1917, was such a day. The sun heats the atmosphere from below, by way of heating the ground, and space cools it from the top. Of course that makes the temperature gradient larger than its adiabatic value.

What time of day day did the descent occur? I think solar heating is the answer, especially as it occurred over the duration of the descent, so that the lapse rate as experienced by the ship was greater than any that existed at any one time. From my recollection of my college meteorology, the lapse rate is not often superadiabatic, and then usually close to the ground, because as soon as it becomes so, convection redistributes the heat  - see. IIRC, fair-weather thermals result from surface superadiabacity in a generally ~adiabatic air mass.

@sdenham: Sometimes the air is unstable through most of the troposphere - that is why thunderstorms are possible. If a cold front passes over western Europe, the air is unstable for several days at a time. Only high pressure means stable air with sun-induced instability close to the ground.

These phenomena are driven by conditional instability from the latent heat of condensation and the difference between dry and wet lapse rates, where the latter is less than the former. This efficiently transfers heat upwards and tends to reduce the lapse rate below the dry rate. If this sort of weather was a necessary factor in this specific accident, perhaps it should be mentioned in the analysis. More generally, as the issue is temperature differences, the compression-heating of the gas should be considered in the analysis, as it is commensurate with the dry adiabatic and exceeds the wet.

@sdenham: I suggest to start gliding and do less theorizing. When you fly gliders you will experience what lapse rate there really is and you will learn quickly that "this sort of weather" is the norm. Also, it's OK if you don't believe my answer, but then please do your own research.

SE comments are a horrible way to discuss matters... I'm not avoiding your point about the conditions behind a cold front, but if the air was unstable that deep for that long, convection would be active 24 hours a day in that time even without condensation, and we glider pilots would not have to wait for the sun to soar. I think what happens is that whenever instability forms, convection brings it back to the edge of instability (i.e. the dry adiabatic lapse rate, if it is clear) ready for the sun to launch thermals by heating the ground (after compensating for overnight radiation cooling.)

I see that our posts have crossed, and if you don't want to address the physics behind your answer, that is fine by me. BTW, the US Navy's inquiry into the loss of the Macon may have some relevance here... I will follow up when I have finished my research.

@sdenham: For the accident to happen it would have been enough for the over-adiabatic lapse rate to exist for the last 1000 m. I was mentioning thunderstorms only because you seemed so sceptic that over-adiabatic conditions could range through most of the troposphere. And regarding thermals: For the vertical convection to start it needs a temperature difference of several degrees. An unstable atmosphere will just stay that way if not "kicked" by some bubble of heated air rising from the ground. Thermals becoming stronger with altitude are clear proof of an over-adiabatic lapse rate.

Assuming that this is a significant variance from adiabatic and is the explanation for the L-55 accident, then it is something that could happen to any airship flying in the lower troposphere in such conditions, and is to some extent a matter of insufficient reserve ballast. As the argument is that the L-55's gas was especially cold on account of the altitude it reached, then the question of compression warming exists  for the descent from there to the lower troposphere.

I forgot to say that I think the need for an additional several degrees to kick off convection is evidence of marginal stability, not instability, and perhaps that might also account for varying thermal strength. There is also a sense in which we may be talking past one another: a km-deep adiabatic surface layer on top of a 10 m superadiabatic layer will appear superadiabatic for any pair of measurements where the lower one is at ground level, even if the dT/dA is only superadiabatic in the lowest layer.

@sdenham: Did you never wonder why gliders and balloons don't fly at the same times? Hot air balloon rides are either early in the morning or late in the afternoon, but never with thermals around. And they fly nowhere near the climb and descent rates of Zeppelins.

What I am mostly wondering right now is why you would risk your reputation with such a blatantly evasive non-sequitur. Clearly there are no answers to be found here, but maybe the physics SE will be more helpful.

@sdenham: Oh boy, I thought that is obvious. The atmosphere has an unstable temperature gradient. On many days. What is needed to get convection started is either the sun heating through the ground inversion and producing overheated air, or and airship which ascends or descends. The process needs a certain kick to get started, either a thermal or an airship. Maybe you ask a new question; I agree that comments are terrible for explaining things. What you think is "proof" of marginal stability is simply inertia in an unstable system.

What should have been obvious is that evidence of the effects of convection is not evidence for that convection requiring deep super-adiabacity. And if inertia is the answer for the delay in convection, and this deep super-adiabacity persists for days on end, why does the convection not continue into the night, or be triggered by night flights? More relevantly, you are persistently avoiding the real issue, which is, even in the presence of this hypothetical kilometer-deep super-adiabatic layer, what effect did compression-warming have on the L55's gas during most of its descent from over 7km?

Maybe the answer lies in the strong wind from the north at altitude, that turned the silent raid into a debacle for the attackers, rather than soaring-type weather in the lower troposphere?

@sdenham: Yes, the strong wind gives a hint, but not what you think. First, back then weather forecasts were rather shaky and Zeppelin navigation, over clouds and at night, was based on expected winds. That L-55 was blown south was less due to the strength but rather due to the wind's unexpected direction. Strong winds equals cold front, and behind a cold front there is high reaching lability - higher lapse rate than adiabatic, in other words. That was L-55's undoing, and it doesn’t matter that you still refuse to believe it. It happened nonetheless.

While Peter Kämpf has addressed the L-55's case, the question asks about loss of lift accidents in general, and the loss of the USS Macon (ZRS-5) provides an additional perspective.
As mentioned elsewhere, rigid airships flew with the lifting gas at the ambient pressure: their lifting cells within the envelope were only partially inflated on the ground, and as the craft gained altitude, they expanded. If they reached their full extent, any additional gain of altitude beyond this ‘pressure height’ would lead to gas being released through safety valves, in order to avoid an overpressure that could rupture a cell.
The demise  of the Macon started with the failure of the incompletely-repaired upper fin, which punctured one or more of the rear gas cells. The officer-in-charge’s response was to drop large quantities of ballast and fuel, causing the ship to zoom well above its pressure height, which was less than 3000 ft., leading to an additional loss of gas. This climb was exacerbated by the change in pitch resulting from the loss of gas from the rear cells, which was not fully compensated for by the elevator man, and which produced additional dynamic lift.
As pointed out by Peter Kämpf, venting gas from exceeding the pressure height is not generally sufficient to leave the ship deficient in buoyancy: given that the amount of gas remaining is sufficient to support it at this altitude, it is sufficient to support it at any lower altitude, so long as the gas is no colder than the surrounding air.  This is a consequence of the ideal gas law (and the fact that hydrogen, helium and air are all very nearly ideal gases at atmospheric pressures and temperatures): a mole of one gas will displace a mole of another if they are at the same pressure and temperature, regardless of what that temperature and pressure is, and so, by Archimedes’ principle, will create a similarly-independent buoyancy equal to the weight of one mole of the displaced gas.
In the Macon’s case, however, losing additional gas would not have helped in dealing with the leakage from the punctured cells, and some forty minutes later, it settled on the water. It is the opinion of historian Richard K. Smith that the excursion above the pressure height was decisive, and without the additional loss of lifting capacity that it caused, the Macon may well have remained airborne. He believes that mishandling of the ship led to dynamic lift contributing to the zoom, in which case the above analysis is not necessarily sufficient, as in the presence of dynamic lift (or upwards momentum), we cannot assume the ship was buoyant above the pressure height.
This is essentially the mirror image of Peter Kämpf's argument: if the airship did not contain sufficient gas to be statically buoyant at the apex of its trajectory, then it did not contain sufficient gas to be so at any lower altitude, a situation that could only be remedied through dynamic lift or by jettisoning weight - something the crew was working on until almost the last minute. Once it became apparent that a crash was likely, the commander had to confront the choice between slowing down or endangering everyone on board, with the former robbing the craft of dynamic lift.
In the case of the L-55, launching with its cells only one-third filled, the pressure height would have been about or perhaps a little above its record-breaking altitude, where the density is about one third of that at sea level. The pressure height of an airship is not fixed in construction, but by the degree to which it is filled before launch.

Flying close to the maximum height was avoided in order to not have the pressure-limiting valves vent the hydrogen gas. Bursting cells were much less of a concern - that needed failed overpressure valves first. And the temperature lag effect works both ways: In case of the Macon, the lift gas was warmer than the surrounding air and accelerated the climb, once that got started. This effect is even sometimes called the aerostatic phygoid.

@PeterKämpf I do not think anyone is suggesting there was a danger of cell bursting, given the presence of automatic relief valves. It subsequently occurred to me, however, that in the absence of such valves, perhaps the biggest danger of over-expanding cells might be to the structure of the airship rather than to the cells themselves - especially in a lightly-built height-climber (though the Macon was more strongly built, following the loss of the Shenandoah.)

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What aircraft can an NPPL SSEA holder fly?
I want to add an SSEA rating to my NPPL license (currently with a Microlight rating) so that I can fly 4 seats.
Wikipedia for the NPPL says:

NPPL holders may not:

fly non-UK registered aircraft
fly "EASA aircraft"

But the NPPL website says

Can I fly my 'N' registered aircraft on my NPPL?
Yes, because the FAA have confirmed that 14 CFR 61.3 permits the holder of a UK-issued sub-ICAO licence, such as the NPPL or LAPL, to operate a US (N) registered aircraft within the UK.

So these two sources seem to contradict each other, can you fly a US aircraft, such as a Cessna 150 on this license or not?
The main reason I want this rating is to fly 4 seat aircraft, so which ones exactly can you fly with this rating?

A Cessna 150 might have been manufactured in the US (or Reims in France) but that doesnt make it a "US" or "French" aircraft for the purpose of licensing. What matters is the state or territory where it is registered.
An NPPL generally lets you fly G-registered aircraft (ie, those on the UK CAA register). What you seem to have found is that there is also a dispensation to be able to fly FAA (ie, N-registered) aircraft too.
As it says on the CAA website emphasis mine

Following an amendment to the UK Aircrew Regulations in 2021, the holder of a licence issued in accordance with the Air Navigation Order 2016 (as amended) (PPL(A) or NPPL(A)) with a valid SSEA or SLMG class rating(s) can now also fly a UK (G) registered Part 21 aeroplane or motor glider.

The two most common four seaters you'll find are part 21 - Cessna 172 & PA28

Thanks Jamie, this helps clear things up. A 172 seems such a big leap from a C42, that it's a bit nuts to me you can technically convert in a few hours...

They're really not as different as you possibly think. Both fairly simple types.

Hey Jamie, so this has only been the case since 2021? Which I assume means it could change again in the other direction in the future

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How many hours in the GA world gets you out of "low time pilot" status?
For the average GA pilot, who might only fly a few hours a month, one might (if they start young enough) accumulate 1,000 hours of flight time in their entire lifetime. I personally expect, if I live and fly long enough, to accumulate between 1,500 - 2,000 during my life.
I hear other pilots being referred to as "low-time" pilots, even though they have 300 hours over 5 years of flying.
So at what point is someone in the GA world not a "low-time" pilot? How many hours?

I just don't think this is defined in recreational flying (which I assume is what you meant by "GA pilot").
The FAA considers pilots with above 1,500 hours to be high-time:

The FAA's desire is that by the time a pilot has their 1500 hours they have developed enough skill proficiency, aeronautical knowledge, and understanding of airport operations to make better and safer decisions in the air.
source

When getting a job, there are some that are considered suitable for "low-time pilots" (probably on their way to those commercial jet jobs). Low-time might be those under 500 hours:

In general, low-time pilot jobs are filled by pilots who have fewer than 500 flight hours or less. source

Studies have been done of predicting accident rates based on total flight hours, which might well hint at which point you become a safer pilot.

Is there a range of pilot flight hours over which general aviation (GA) pilots are at greatest risk? More broadly, can we
predict accident rates, given a pilot’s total flight hours (TFH)?

With a broad conclusion that accident rates do seem to tail off quite dramatically somewhere around the 1,500 hour mark - quite probably the reason why the FAA use this number.

Anecdotally, at around 400 hours I very much consider myself a "low-time pilot". I am also consciously aware from speaking to peers that 300-1000 hours is where pilots feel (over-)confident in their ability, and possibly make the most mistakes.

“Low time“ is a relative term. If the FAA is considering a person with 1500 hours to be a “high time pilot“ you’re kind of at the bottom of the barrel in terms of pecking order in the airlines. I have a friend out in Idaho, who is a retired 747 captain with over 35,000 flight hours over a 40 year long career.
Military pilots have considerably fewer hours. A person with a 15 to 20 year long career as a pilot in the armed services may only hold less than 4000 hours total time, simply because of the cost to operate some of their aircraft.
High time may also be relative to your competitiveness in terms of hire ability.  Even a 1500 hour pilot may not be competitive to be hired by many companies, particularly if those hours are largely accrued in light single engine airplanes with a little to no multi engine and/or turbine time.  Flight environments, locations where time was logged, seasons, weather, instrument flying experience, night flying experience, type ratings and familiarity with different aircraft types and avionics all come in to play here as well.

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What are the wind speed limits for skydiving?
Obviously, there is the crosswind and steady wind speed limit of the aircraft you are jumping from, but that aside, what are the wind speed (including gusts) limits for the average tandem skydive?

Skydivers should have personal limits, just like pilots do. Landing safely becomes more and more difficult with higher wind speeds and with higher gust factor. This refers mainly to the ground winds- skydivers in the air don't "feel" the wind speed anymore than a plane does.
The USPA sets limits on the maximum wind speeds for solo student divers in its Basic Safety Requirements, of 14 mph with a ram-air canopy and 10 mph with a round reserve. It does not set any hard requirement for tandem dives or solo dives by licensed divers. It is up to the individual diver to decide what is safe and what is not based on the conditions and their experience level.
Of course, if you're not jumping from your own plane into your own drop zone, whoever operates the plane or the drop zone may have their own more restrictive limitations.

It is also up to the dropzone which will have thresholds for sustained winds and gusts.

@SDH Good point, added.

Ok, but there must be an average number! 20kts, 25kts?

@Cloud Sure. 20-25 knots is probably about right for experienced skydivers.

@Cloud Here is a good reference article: https://www.skydivecsc.com/blog/know-your-skydiving-wind-limit


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Can you disengage A320 autopilot with stick pressure?
I was recently reading that in most military jets, auto-pilot can disengaged without hitting the button, by applying 5lbs of pressure to sticks.
Does this work in commercial airliners such as the A320?

Yes. I’m not sure of the amount of force, but from the A320 FCOM:

AP DISENGAGEMENT
AP1 or 2 disengages when:

The pilot presses the takeover pushbutton on the sidestick.
The pilot presses the corresponding AP pushbutton on the FCU.
The pilot pushes on the sidestick harder than a certain threshold or moves on the rudder pedals above a threshold.
The pilot moves the pitch trim wheel beyond a certain threshold.
The other AP is engaged, except when localizer/glideslope modes are armed or engaged, or when the rollout or go-around mode is engaged.
Both thrust levers are set above the MCT detent and the aircraft is on the ground.
The aircraft reaches the MDA-50 feet (MDH-50 feet), or 400 feet AGL if no MDA/MDH, with APPR mode engaged and a non-lLS approach is
  selected.
One of the engagement conditions is lost.

Furthermore, in normal law with all protections available, the AP will disconnect if:

High speed protection is active;
Angle-of-attack protection is active (α prot + 1° is reached);
Pitch attitude exceeds 25° up, or 13° down, or bank angle exceeds 45°;
A rudder pedal deflection is more than 10° out of trim.

The standard way for the flight crew to disengage the AP is to press
  the takeover pushbutton on the sidestick. When the AP is OFF, the
  associated FCU pushbutton goes off. and "APl" (or AP2) disappears from
  the PFD’s FMA.
*emphasis mine

While not an A320 per the OP's question, the case of Aeroflot Flight 593 in 1994 details a case where the partial disengagement of the autopilot on an A310 by means of continued pressure on the controls contributed to the crash. (massive oversimplification, look at the Wikipedia page linked above for more details)
The circumstances that led to the crash of Aeroflot 593 were addressed in later revisions of Airbus aircraft to the point where you would know it if the autopilot disengaged due to conflicting control stick inputs.

From what I could gather, airliners such as the Airbus A320 have a red button on the sidestick that will disengage the autopilot should you press it. The autopilot can also be disengaged by moving the control stick though this is not usually recommended as it can cause the aircraft to roll suddenly.
Airbus aircraft have an autopilot panel such as this one below that controls the autopilot:

https://en.wikipedia.org/wiki/Autopilot#/media/File:A340_FCU.jpg
Places I got my info from:

quora.com/How-do-you-disconnect-the-autopilot-in-airliners
aviation.stackexchange.com/questions/149/what-are-the-main-differences-piloting-boeing-vs-airbus-aircraft

Hope this helps. And if anyone feels like I stole your info, I apologize.


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What is the horizontal stabilizer failure procedure?
During the final flight of Alaska Airlines Flight 261:

The CVR transcript reveals the pilots' continuous attempts for the duration of the dive to regain control of the aircraft. At one point, unable to raise the nose, they attempted to fly the aircraft upside-down.

I was wondering what the actual procedure is, if the horizontal stabilizer has a complete failure like this? Do commercial pilots ever simulate such scenarios?

Thanks @ymb1 , I had a look at the question but that scenario is not as extreme as the one referenced here. :)

Only a comment instead of an answer, because it refers to small sport planes and gliders: You can land with a complete loss of elevator control, by using the elevator trim. However (on the model I was flying), it is recommended in the instructions manual to jump out with the parachute, as this procedure is extremely difficult. My instructor did land it once only with the trim. I once did it in a simulator, although on a different model. So there are aircraft where it is possible.

@vsz Landing with complete loss of elevator is a documented procedure in transport aircraft and is practiced in sim. It's an issue on FBW aircraft when you have loss of certain combinations of hydraulics and electrical/computers at the same time.

This would fall under catastrophic failure and theres not much that can be done. You may as well ask what will happen if a wing falls off.
but..
UA232 Sioux City. The #2 engine (in tail) blew up and took out the hydraulic lines rendering all tail control surfaces (horizontal and vertical) inoperative. The crew found they could regain limited control of the attitude of the aircraft by varying the thrust on the wing engines, increasing thrust gave some pitch up, decreasing thrust-pitch down. This was due to the line-of-thrust being below the wing. The crew did a great job of getting the airplane back to the airport and heading down the runway. Even though it cartwheeled and burned, a lot of passengers survived, thanks to the crew's action.

F-15 Pilot lands with one wing

@RonBeyer Read the article. Still don't understand how lift can be generated through engine intake without a wing. Amazing.

@Cloud The F15’s body is similar enough in general shape to a wing so that given enough speed and the right attitude relative to airflow, it generates some lift (same as any other flat-ish body).

@CptReynolds, the F-15's high thrust-to-weight ratio (greater than 1 under some circumstances) certainly helps.

@Mark Agreed. Or, as one of my propulsion instructors used to say: “With sufficient thrust, anything flies!”

Yes it is done regularly on recurrent sim training, but not to full travel because it is normally treated as a control system fault that can be stopped before it becomes totally uncontrollable, and the Alaska Airlines incident was a mechanical failure of the acme threads on the screw jack where the stab was free to tilt up as far as it could go and they were doomed.
In sim training usually the instructor will generate a stab runaway while you're in some settled down situation minding your own business, and you have to recognize it (there is usually a clacker sound that goes off after it has run for more than say 5 seconds if you don't notice the indication moving), hit the stab trim DISC button on the wheel to disengage the trim channels, and do what ya gotta do.  If the autopilot was on in ALT hold mode it would have disengaged itself at some point also when the elevator force required to hold altitude got too high and exceeded the torque limit on the autopilot servo.
What you are now faced with is an airplane that is now trimmed for a single speed, wherever the stab stopped at, and to fly at any other speed requires you to displace the elevator and hold it there, against the springs in the pitch feel system wanting to return it to neutral.  So it all depends on how far the stab moved before you cut it off.
Nose down runaways are generally worse than nose up runaways, because it's easier to push and hold then pull and hold, because you can jam your leg against the column to give your arms a rest on a nose up runaway.  Stab runaways are one of the more unpleasant training scenarios especially because if you get a nose down runaway (which depends on the evilness quotient of your instructor) your arms are going to be really sore when you're done.
Most airplanes have significant trim change with flap extension and flaps can be deployed to help with controlability depending on the airplane's response to flap deployement, so that's a case where knowing your airplane can really help.
Although the AA261 incident did absolve the jackscrew grease as a root cause, it did cause a review and testing of grease intermix practices (the jackscrew had both lithium grease and clay base grease on it and the grease was degraded), where it was found that mixing lithium base and clay base greases caused premature breakdown, and an industry wide campaign was done.  Most maintenance manuals have admonishments against mixing clay and lithium grease.
Problem is, there isn't a separate mil-spec for clay and lithium, only between moly and non-moly grease, and greases may only be called for by the mil-spec not brand name, so the situation, to this day, can be bit of a mess.  For example, Aeroshell 33 (lithium) and Aeroshell 7 (clay) are the same mil-spec, but are not supposed to be intermixed.  Clear as mud?

I was wondering after reading your answer... why don't the controls feature a 'lock' option... i.e. you could pull up as far as possible and then click a lock mechanism to hold it there so your arms don't fatigue?

That that would be like having a steering lock option so you could let go of the wheel on off ramps because you have to manhandle it after the power steering crapped out.  The probability you will end up in the weeds is pretty high.


text:
Do all airports have the authority to impound aircraft for overdue fees?
In the 'Collapse' section of the Thomas Cook Wiki, it states that

At around midnight on 23 September, airports in the UK began to impound Thomas Cook aircraft upon arrival, citing "default in payment of airport charges"

Do all airports have authority to do this? If I refuse to pay a $15 landing fee in a Cessna, can they impound the aircraft?

What country are you asking about?

@Bianfable Thomas Cook is a UK airline so would be a good default. That said, question uses dollars, so anything is game.

If you don't get a good answer here you might try law.SE as well. There could be some general contract law issues that apply to an aircraft, car, boat etc.

Yes, at least if the airport is city owned (or owned by a municipality). For example Philadelphia's airports are city owned and they have landing fees as well as default repercussions

1.05. Payments
Non-tenant Air Carriers and Operators not providing adequate surety or
  security in form and amount satisfactory to the Department of
  Commerce, to ensure payment of fees and charges, shall be required to
  pay all incurred fees and charges prior to aircraft departure.
...

If any charges remain unpaid for a period of twenty (20) days after the due date,
the City may:
a. Bar operator from the Airport and
  the use thereof; and/or
b. Deny operator the use of Airport
  facilities; and/or
c. Commence such actions at law or in equity as are
  deemed in the best interests of the City.

I see no reason impound would not be covered under section C there. Privately owned airports are a different situation but I imagine they have some kind of legal recourse.

A private airport, should local legislation not permit impoundment, can simply deny the aircraft the services necessary for takeoff, such as ground handling, fuel or ATC -services.
In (the likely) case these services are provided by a (sub)contractor, the airport can simply forbid the contractor from providing these services. The company facing the impoundment propably has unpaid bills here and there, including the aforementioned service providers, so they are propably happy not to serve the grounded plane.
So even if the plane in question was not legally impounded, seized or confiscated, it won't be going anywhere.

That would probably be a breach of contract by the airport and challenged in court

@Diego Sánchez well the starting point of this situation, as the question stated was "default in payment of airport charges", so good luck with going to court with a case "I didn't pay for previous services so they declined to serve me" :)

I don't know. If you refuse to pay your water service charge in your home, your water provider is still legally obliged to provide you with running water.

@Cloud utilities such as water and electricity are not comparable to airport services in question. Only exception I can think of would be a situation where the airport is the sole connection of, say, a remote island or such, to the outside world, and denying service would impose an immediate threat to the safety and health of the local community. How about if you don't pay your phone bill, bet you won't be making calls ;)


text:
How can I get a ride in the jump seat as a non-professional pilot?
A couple of years ago, I had a strong fear of flying. Now, I really enjoy it. In fact, it is a dream of mine to sit in  the jumpseat of an A320 during takeoff. I've had a handful of flying lessons.
If I took my logbook and explained my interest to the captain, is there any chance this could happen? If not, how could I make it happen?

@ymb1 Not the same. I usually get a visit to the cockpit post-landing with every flight. I want to see a takeoff.

Probably not, unless you're Sam Chui, who has done this many times with many different airlines.

Very much not an A320, but some seaplane operators allow you to sit in the co-pilot's seat on commercial flights; Harbour Air in Canada for instance allows you sit there with the pilot's permission; you just have to ask as you board. These are very small aircraft though, around a dozen or so passengers...

Do you have the available capital to just... buy one?

All I can say is if you find a way to do that on a commercial airline, please let us know what airline it is so I can never fly on it again.

It's hugely unlikely. Almost vanishingly unlikely, with few exceptions perhaps for something a little smaller than a passenger-carrying A380 (like a private jet on a repositioning flight where you know the captain well)
You used to be able to go up and see the captain on the flight deck - I did it a few times as a kid. Even then asking to sit in the jump seat was usually met with a smirk.
And then 9-11 happened.

With effect from 1 November 2003, ICAO Annex 6 was amended so that under Chapter 13.2.2 “all passenger-carrying aeroplanes of a maximum certificated take-off mass in excess of 45 500 kg or with a passenger seating capacity greater than 60 shall be equipped with an approved flight crew compartment door that is designed to resist penetration by small arms fire and grenade shrapnel, and to resist forcible intrusions by unauthorised persons. This door shall be capable of being locked and unlocked from either pilot’s station”.

And with that came locking of the cockpit door, and no more visits to the cockpit during flight (incidentally, if you ask nicely, the captain will often let kids take a peek when they're deplaning the passengers)
And then germanwings happened, and they had a rethink. But still no visits to the cockpit during flight at all for the average Joe.

"But still no visits to the cockpit during flight at all."  Not true, although this is company dependend. You might get to sit in the cockpit, even for the entire fligh, but you'd have to be related or a very good friend of PIC or SIC.

@Jpe61 ok, if your dad is an A330 pilot, you might get lucky. Mere mortals: no chance. Answer updated.

Nope: as I stated, relative or good friend is enough in some companies. Been there, done that @Jamiec

@Jpe61 I would be literally amazed if any carrier allows this these days, even for close friends, even for family members. As I alluded to in my answer, I have stood just behind the Captain and FO in the doorway on a private jet re-positioning, but that same Captain now works for a tiny regional airline and there is no way I could do the same now. YMMV.

You may choose to believe me or not @Jamiec , really makes no difference as this is the internet, and here your reality is as good as mine when compared head to head. There is one large carrier that I know for certain that facilitates jumpseat travel in the manner I've described, and some others that I've heard of doing so.

....and thats why I included YMMV. Look it up.

@Jpe61 Can you name the carrier please?

@Jamiec oh, I get it now, sorry. I still do think your answer is too strict. You see, statistically I'm about as average as a Joe comes (funny how you happened to pick that phrase), and on some flights I do have the opportunity to occupy the jumpseat. Rare among any population, yes, extremely rare (like one in a million), no.

@Cloud I'm sincerely sorry, but no. This is a sensitive issue to some clientele for feeling of safety, hence (and propably many and other reasons)  not even the official carrier spokespersons are likely to discuss this in public. Even if I told you, it would not benefit you in any way, as you'd still have to have a strong connection to a pilot. If you have some, ask them.

I will just leave this here: https://edition.cnn.com/travel/article/china-pilot-suspended-cockpit-photo-intl-hnk-scli/index.html

There was also Aeroflot flight 593, in which the pilot allowed his son to sit at the controls, and the worst possible outcome happened.

@Moo: banned from flying for life seems...reasonable, especially given MichaelHampton's reminder about Aeroflot 593.

As a non-professional pilot, to get a ride in the cockpit jumpseat, you'd have to meet at least three conditions:

company policy must allow passenger in jumpseat
PIC must allow passenger in jumpseat
you'd have to be well known and trusted person to either SIC or PIC (preferrably PIC)

If you fail to meet any of those, no jumpseat ride for you. So, very slim chances, but not impossible.
The aforementioned is based on personal experience, multiple occasions, and applies to a major intercontinental airline which I will not name.

My dad, a complete stranger to the pilots, got a jumpseat ride on a 737 around two years ago. A passenger fainted during taxi and he (general practitioner) helped sort things out. During cruise FA's came up to him and asked if he would like some token gifts as a thank-you. He jokingly said he'd prefer a visit to the cockpit. A while later he was very discreetly ushered into the cockpit, where he had to stay, cockpit door locked, until all other passengers had deplaned.

I got a cockpit ride on an Air France domestic flight a few years ago (pre-Germanwings) with a school buddy. We asked nicely, said we were students at the aerospace engineering school that neighbors the major French airline pilot school, said it was a lifelong dream, the pilots happened to be from that pilot school and indulged us. My buddy did the first half of the flight (takeoff just behind a landing A380 test flight) and I did the second half, a beautiful nightly cloudy approach into LIL.

@TomvanderZanden - So, flight school or med school I guess.  Your choice...

It's not necessarily what you know, It's also who you know.

I regrettably inform you that your chances are very slim, outside of actually completing the training required to fly the aircraft.
In this world where aircraft terrorism is always a concern, you would have to have a very good reason to convince the captain why he has to put a complete stranger in the cockpit. To the captain, the stranger is simply someone claiming to have flight experience. To the stranger, it may be an experience; to the captain, it is a routine, daily job, with schedules, policies and regulations to follow.
In my airline, this would be strictly against policy. Even if we were to jumpseat a flight attendant, there has to a necessity to do so (e.g. no rooms in the cabin / broken seat etc.)
There are companies that provide simulator rides to the general public. There are none that provide a jump seat ride as far as I've heard.
Disclaimer: I am not affiliated with the linked company.

what do you fly? Can I personally arrange this with you instead?

"Kevin, meet @Cloud. Cloud, meet Kevin." There, now you're not complete strangers! I don't think that's going to make someone you've "met" on the internet consider you not a safety risk. If you've been next-door neighbors for the last 10 years, you go to church together, your kids are on the same soccer team and you're regularly invited over for a BBQ, you're probably well known enough for a PIC to put his neck on the line for you. But, you never know...

@FreeMan ... and then there are neighbors of whom we say in retrospect "but they have always been so calm and nice" ;-)

yeah, @PerlDuck, the neighbors always say, "He seemed so nice and quiet. He always kept to himself..."  I figure that between the BBQ attendance and the spouse/kids-in-soccer requirement, though, that should eliminate most of the Uni-bomber types. ;)

@FreeMan Yes, of course. I was more or less kidding. You just can't get into another person's head.

I would suggest to purchase a training session for A320 in a certified flight simulator like this one, for instance. I understand this is not a real flight, but these simulators feature full scale cockpits with all controls, and the realistic algorithms to simulate the flight itself.
A after the instructor giving you an introduction, you will be able to take the controls yourself during take off. This may work pretty well as a counter-measure against the fear of flying.

This is not really direct answer to the question 'as-is'.
It's more answer to  'how can a Non-Pilot' fly regularly in the jumpseat.
Just become Flight Dispatcher.
In many airlines that gives you 'Known Crew' badge. And with it and PIC permission you can fly in the cockpit as much as you wish. Dispatchers even trump flight attendands in that regard. Regular jumpsitting is part of the work actually. Some FDs just use it as a meaning of commute - in the US per ALPAs rules AFAIK.
The catch - in the EU the training is 2000 EUR, the course requires you to pass 14 exams - the very same as for ATPL :D
&

authors: Bob Jarvis - Слава Україні


text:
Does the ditching switch allow an A320 to float indefinitely?
I watched a documentary yesterday about the Hudson River ditching of US Airways Flight 1549. In the documentary, one of the investigators explained that the reason the water was entering so quickly was because the FO did not have time to hit the 'Ditching' switch the A320 is equipped with. This switch closes all vents etc. to prevent water from entering the cabin.
If an A320 or similar is ditched and the switch is activated in time, does that totally prevent water from filling the cabin (in a best-case scenario)? I'm thinking if one ditched in the Atlantic and had to wait for hours for help, would it be possible to stay afloat for so long?

Actual boats won't stay afloat forever without additional help!  But "long enough for rescue" is a good criterion for this scenario.

There was significant damage to the rear lower fuselage, so it is not obvious how much water intrusion the ditch switch would have prevented anyway:  http://www.flyian.net/aircraft/museum/ncam/1549/1549.htm

US-1549 was floating for two days after the landing into water even without the switch.

Using the word indefinitely seems to trigger a lot of besserwissers, maybe you need to change the title a bit.

The answer is no, not totally, but it would really slow things down. I don't think anybody knows the precise answer because only flat water ditchings seem to result in the airplane stopping in the water in one piece (such as 1549 and a similar one in Malaysia) and flat water incidents (like Malaysia and some airport overruns) are usually in shallows where the ditching valve is moot.
But assuming an A320 was able to ditch on open ocean swells without breaking somewhere, certainly it would float for a much longer time, but not forever. Pressure hulls are never absolutely fluid tight; door/hatch seals leak a little bit, and there may be tiny leaks through various entry points below the water line like bleed air shutoff valves, fay-sealed skin laps, rivets, control cable pressure bulkhead fairleads, etc (the older the airframe the leakier).
Wing dry bays may be sealed off with a tape made for the purpose but they are not usually totally water tight.  Water can migrate into the fuel tanks through the vents.  Full fuel or nearly full fuel would be a bonus, fuel being buoyant.
You certainly would have a lot more time to get onto the rafts (perhaps Airbus has estimated the theoretical sink time by calculation), but it would sink eventually (it would take quite a few hours, maybe even a day or two), and you aren't going to be staying on board any longer than necessary regardless.
(Now, if you ditch in a composite foam sandwich sailplane, well you've got yourself an unsinkable boat right there, and if you took a paddle along, you could actually go places.  If I'm in a glider that gets low over rough forested terrain, and there are lakes around, I'm putting it in the water and paddling it to shore with whatever I have at hand).

Unsinkable, huh? Is your sailplane named Titanic? :)

In theory, yes.  In practice, no.
FAA regulations (specifically, 14 CFR 25.801(d)) require that, under reasonable water-landing conditions, an airplane must remain afloat long enough for the occupants to evacuate.  Most airplane manufacturers don't actually test the ditching performance of their aircraft, but instead rely on the clause of paragraph (c) to let them compare their airplane to a similar one that has been tested.
The A320 is certified based on ditching tests of a scale model of an Airbus A300 done in 1974.  Under the landing conditions specified in the certification, the A320's fuselage is supposed to remain intact in the event of a water landing, and with the "ditch switch" activated, water entry is supposed to be minimal.  (Flotation won't be truly indefinite, but when the main source of water entry is things like leakage around door seals, it's quite possible to stay afloat for days or longer.)
If you read the investigation report from US Airways flight 1549, the specified landing conditions were found to be nearly impossible to attain in the event of a dual engine failure.  Flight 1549 actually hit the water with the nose lower than specified, producing a higher vertical speed and a greater glideslope angle, causing significant structural damage.  Specifically, a number of lower aft fuselage panels were buckled or torn, letting water freely enter the airplane.  In this situation, the use or non-use of the "ditch switch" is irrelevant.

NO. Indefinitely is a very, very, long time. In fact it's so long that by the time it's over there's no more water for the aircraft to float in. Heck, there's no more planet for the water to exist on.
But even for a shorter period, say hours, it wouldn't work. The switch may close some holes, but the doors would still be opened to allow egress into life rafts. Wave action may break windows and erode door seals pretty quickly.
And there has to be some holes still open to allow air circulation into the cabin to prevent everyone inside suffocating. Water can enter through those as well.
The switch is there so slow down water ingress to allow more time for evacuation, not completely prevent it. That's all it is designed to do, and that's all it does. It's not designed as nor does it work to turn the aircraft itself into a life boat for the crew and passengers.

I find it hard to believe that wave action would break aircraft windows -- are you sure about that?

The A320 floats nose-high, with the front and overwing doors well clear of the water.  It would take pretty significant wave action to get water to flow in through them.

If the fuselage is intact, it would slow down the ingress of water due to the inability of air to be forced out.  Open the exits and all bets are off.


text:
How was this airline (statistically) never had a fatal incident?
Ryanair make around 725,044 flights per year. This They have been operating for 35 years, so have accrued around 25,376,540 flights.
They have also never had any fatal incidents or even major injuries related to a flight. Statistically, they should have had around 2 or 3 by now at least.
How and why is this airline so much safer, statistically (based on average commercial aviation fatality statistics) than almost any other airline in the world? (Easyjet being the closest with a similar perfect safety record).

Statistically, they should have had around 2 or 3 by now at least. I don't think that's how statistics work.

I don't think you'll get a definitive answer here, but with a large number of airlines it's always likely there will be one or two airlines which are outliers by chance. You would need to test the null hypothesis with something like chi-square to be sure. Lots of work....

It's like saying, "My grannie drove her whole life without a speeding ticket, when most people get a couple in their lifetimes.  How could she do that?".  Reminds me of an old comic strip gag where a guy with a clean driving record for years and years is complaining about his insurance rates skyrocketing.  Insurance agent says "you're due".

A seemingly minor but very important detail.  Are you asking specifically about Ryanair, or did you look through a list of aircraft accident rates and are asking about the lowest one?  If the real question here is the odds any airline go without any fatal incidents, well that's probably 50 times more likely.

Your number of total flights are way off. They have operated for 35 years, but haven't had that number of flights per year for long. Their fleet numbered 383 aircraft in 2017, but just five years earlier it was around 100 less. I can't find historic numbers, but according to Wikipedia but during the first few years they only had a handful of routes.

First of all, Ryanair has more than 700,000 flights per year now, but not during their entire 35 year existence. The total number of flights you give is therefore too high.
Assuming aircraft accidents are purely statistical (which is not true, of course), one can estimate the number of accidents you expect using a Poisson distribution: the probability of having $ k $ incidents with $ \lambda $ expected incidents is given by
$$ P(k) = e^{-\lambda} \frac{\lambda^k}{k!} $$
To get the expected number of incidents, we take the overall accident rate of 1 in 2.5 million flights (aviation-safety.net, for 2018, has been higher during the last 35 years) and multiply it with the total number of flights. For 25 million flights this would be $ \lambda = 10 $. This results in in a probability for 0 accidents of only $ P(0) \approx 0.004 \% $. Even when assuming 12.5 million flights in total (as suggested by David Richerby in the comments assuming a linear increase from 0 to 700,000 flights per year), one still obtains $ P(0) \approx 0.67 \% $ with $ \lambda = 5 $.
This means Ryanair is indeed safer than the average airline flight world wide, but so are many other EU or US airlines. Safety is not just a statistical coincidence, regulations are very strict in Europe and training is good resulting in higher than average safety records.

Indeed, if we assume that Ryanair started with zero flights per year (which they did!) and have linearly ramped up to their current volume (which is less accurate), then we estimate that they've had about half the number of flights that the asker claims. In that case, the claim of "should have had around 2 or 3" accidents needs to be revised to "should have had around 1 or 1.5". Well, it's not so surprising if a number that "should be" 1 or 1.5 turns out to be zero.

@DavidRicherby thanks, I added the estimate to my answer.

@DavidRicherby Also, the 1 in 2.5 million statistic applies to incidents, fatal incidents however are much more uncommon at around 1 in 11 million flights.

@Cloud No, I quote from the page I linked: "the accident rate is one fatal accident per 2,520,000 flights". This is for fatal accidents (in 2018).

@Bianfable Apologies... that is surprising. Next you'll be telling me my roulette technique is wrong (I wait for 3 reds or blacks in a row and then bet on the opposite colour, since although each spin should be a 50/50 chance, the likelihood of 4 in a row is much smaller than 50%)...

@Cloud - not sure if  that was a serious comment but yes that roulette technique is wrong.

@Cloud There is no such thing as a "fatal incident" in aviation. It's either an incident or an accident, where IIRC "accident" is defined by the existence of non-trivial injuries, fatalities, or significant airframe damage. An in-air near-miss averted by TCAS RAs with no injuries would, again IIRC, constitute an "incident".

Each time you interpret statistical values, you need to look at both, the mean value and the mean deviation.
The mean value of incidents per flight per year gives you the expectation value. That would be the 2 to 3 that you cited. Now you have to look at the distribution. Many statistics are shaped like the famous Gauss bell.  The statistic of accidents per airline probably has a different shape because of the small numbers involved. A Poisson distribution maybe comes closer.
The point is, if you are reading a statistic result, where the expectation value is 2.5, and the mean deviation is 3, then 0 incidents would mean no significant deviation. There wouldn't be enough data to tell if the airline is safer or just lucky.


text:
Is a certificated pilot considered to be a student pilot when training in a new category or class?
Inspired by this question, is a pilot certificated in one category or class considered to be a student pilot when training in a new category or class?
To take a specific example, if a pilot holds a Private Pilot - Glider certificate and then decides to add ASEL, is he considered a Student Pilot while he's training for his ASEL? By "considered" I mean, do regulations that refer to "student pilot" apply to the pilot?
Or, to put it as simply as possible: what is the FAA's regulatory definition of "student pilot"?

No.  The regulations that apply to a student pilot do not apply to the private pilot working on a new category or class rating.

§61.81   Applicability.
This subpart prescribes the requirements for the issuance of student pilot certificates, the conditions under which those certificates are necessary, and the general operating rules and limitations for the holders of those certificates.

The required endorsements for a private pilot working on a new category or class rating are also different.  Student pilots are required to have endorsements for pre-solo flight training, a solo endorsement each 90 days and an endorsement for each cross country.  The student pilot must also abide by all the limitations placed on those endorsements by the recommending instructor.
A private / commercial / ATP pilot working on a new category or class rating is required to have one endorsement.  Again, any limitations placed on the endorsement by the recommending instructor must be followed.

A.72 To act as pilot in command of an aircraft in solo operations when the pilot does not
hold an appropriate category/class rating: § 61.31(d)(2).

I certify that [First name, MI, Last name] has received the training as required by
§ 61.31(d)(2) to serve as a pilot in command in a [specific category and class] of aircraft.
I have determined that [he or she] is prepared to solo that [make and model] aircraft.
Limitations: [optional].

Required endorsements for FAA certificated pilots are found in AC 61-65. Version H, issued August 27, 2018, is the latest as of May 2023.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
What warning lights can one safely fly with?
Like many people, I often either ignore or reset warning lights in my car and continue to drive without issue for months or years (usually due to dodgy sensors giving a false-positive).
What warning lights can we still complete a flight with in small aircraft (Piper Tomahawk, Ikarus C42, Cessna 150s and such)?
For reference, I have read on other discussion forums that C150s often have the low voltage & low oil pressure issues. People have ignored them and crashed... I don't want that to happen.

For warning lights in a car: don't just assume the light is due to a faulty sensor, but check if this is true. If it is, AND the light does not warn for a critical item, you could consider to keep driving. But be aware you've just reduced your margin for error: you've lost whatever function the light was supposed to warn you about.

@Hobbes Or, at the very least, you've lost the ability to notice a real problem with whatever function the light is supposed to warn you about in advance of actually needing that function.

Ignore or reset the warning lights in a car? You mean the ones that tell you there's a flat tire, or you're low on oil and your engine could seize up, or your brakes are about to stop working? Even if it's a non-safety related sensor failure chances are your performance or mileage will suffer, or cause long term damage which will be more expensive later. Don't ignore them in a car, and certainly not an airplane.

Why the downvotes

@cloud: Because it's a terrible idea to ignore warnings in an aircraft.

@GdD:  The yellow light on my dash for "Add Washer Fluid" light has been on for the past several months.  Do you think my performance or mileage is suffering?  Am I causing long term, expensive damage?

@GdD case in point: my car has a warning light for the power steering. It's stuck in a 'half on' state. After careful consideration (a readout confirms no actual failure of the power steering, the only remedy is replacing half the dashboard, and power steering failure is both obvious and noncritical) I've decided to keep driving.

Next time you get crud kicked up on your windshield on a crowded highway at night and can't see out the answer is likely yes @abelenky.

In general, the procedure will be to exercise good pilot judgement. In many cases, this will include or begin with pulling out the checklist and/or performing memory items from the checklist.
Small airplanes don't have the huge array of sensors that airliners are equipped with. Especially in an ultralight like the C42, you might be lucky to have a few engine instruments and a master caution/warning light.
For example, in the C42 that I fly, the typical reason for the master problem (really, a combined master caution and master warning) light to come on in flight is that the cylinder head temperature is too high, in which case in that airplane the appropriate action is to fully open the cowl flap and to reduce power but generally to maintain speed, to allow the engine to cool down in a quick but controlled manner allowing continued flight; then adjust the cowl flap for the current flight regime. The way to verify that this is actually the problem is to look over at the CHT gauge and see if it's above the green arc. However, if it's not the CHT, that same light might come on for, say, an electrical problem, which would call for an entirely different set of actions in response and might require landing soon, before the battery is depleted.
The lights only really serve to direct the pilot's attention to the fact that there is a problem.
I agree with Sanchises' point to never ignore warning lights, or for that matter other indications of problems, in an aircraft. Heck, I don't ignore warning lights even in my car, let alone in an airplane. (I don't know how many times I've told my instructor something along the lines of "it wants attention" as I started to scan the instruments specifically to see what problem caused the problem light to come on.) That doesn't mean that the appropriate response for every problem is to land immediately.
On the flip side, in extreme situations, it might be appropriate to continue flying even with something like a low oil pressure indication, which if determined to be accurate (which you can't always rely on, and certainly can't assume; it's the old adage, trust but verify) would normally call for an engine shutdown and engine-off landing. To keep flying with low oil pressure will quite possibly ruin the engine, but if the alternative is a crash landing or a ditching over open water, then it comes down to that rebuilding or replacing the engine is likely to be cheaper than would be replacing the entire airplane. Either way, though, in such a situation you make an informed, conscious decision on which action to take in response to the problem. Following the prepared checklist for diagnosing and dealing with the problem in that particular airplane should be the first step in that process.
Expect great fun when you're just entering the downwind leg for landing, or are at low altitude and near the end of the runway during climb-out, or over the woods, or some similarly precarious situation, and the instructor tells you "we have an engine fire, now what do you do?".

@Cloud Properly maintained airplane engines are actually supremely reliable devices. The one exception to this is in the case when a certified flight instructor or flight examiner is sitting in the next seat over, at which point they tend to develop problems every few minutes or at least once or twice per flight. You get used to it. Just don't grow to rely too much on the engine magically restarting.

The items that need to be operational for an aircraft to be considered airworthy are laid out in the Minimum Equipment List (MEL).
In-flight, follow the appropriate checklist for the warning light. Typically, it calls for troubleshooting the problem, and if the problem persists, directions on how to continue. Options typically range from "continue flying" (for example, vacuum failure could allow for partial panel procedures), "land as soon as safely possible" to "initiate forced landing" (engine fire).
As a general point of principle, don't ignore warning lights in aircraft. If it wasn't a problem, it wouldn't have a warning light.

This applies before departure. But I am also considering scenarios where you are in the air and a light comes on. At this point, you need to decide whether to continue or turn back I suppose.

@Cloud In-flight, always follow the appropriate checklist.

Looking at your typical Cessna 172 there will be perhaps 2 warning lights:

After start warning light: this tells you the starter motor has not disengaged. If you ignore it you can cause serious damage to the engine. Stop your engine immediately using a lean cut-off and terminate the flight, informing maintenance
Low alternator voltage: this tells you the ammeter is not showing a positive battery charge. If the battery isn't charging then your battery will die and you'll lose all your electronic instruments and avionics, including transponder and radio. Try cycling the alternator side of the master switch off and back on and see if it starts charging. If the light goes away then keep an eye on it and get it looked at by a mechanic, if the light stays on turn off all non-essential instruments and avionics to preserve your charge and divert if you aren't close to your destination. Inform ATC

Don't ignore warning lights.

As I recall, the 172s I flew also had low vacuum warning lights in addition to the lights you mentioned.


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How long can ATC operate for without main power?
This question pertains to large towers at large airports. I'm assuming there is backup power in case of a power cut / power failure. But how long does a typical reserve generator / unit supply power for and what happens if it runs out without a main supply back online?

I'm not sure it's clear what you're asking. Generators run on fossil fuels, so I guess they'll keep running until we run out of fossil fuel to use?

Remember, too, that if ATC goes out a a specific airport, all operations revert to IFR, so the airport doesn't technically have to close (assuming the weather remains IMC). Anything in the air that can't land will divert. Additionally, in the US (or anywhere American troops are stationed), there will be mobile military units that could be moved into position to provide service/assistance if necessary for more long-term solutions.

@FreeMan Do you mean VFR & VMC, rather than IFR & IMC?

@RalphJ umm... yeah... that's the ticket...  :blush:

A nearby ATC facility I am familiar with has a backup generator which will run their ATC functions (TRACON and Tower), and is fueled to run for 4 to 5 days.  After that time, it needs more fuel.  After two weeks, it needs periodic maintenance (oil change, etc.).
The on airport approach radar has a separate generator at the radar site, which can run for about three days before needing refueling.
The airport has several backup generators.  The ones which run the airport lighting are not capable of running all the airport lighting, and do not power the beacon which is at a perimeter of the airport and without backup power. I do not know how long the airport lighting can be operated.
Some of the NAVAIDs have migrated off backup power.
The terminal building has several generators, and I do not know what their duration or backup coverage is, but I would guess they can partially run the passenger terminal for a day or so.
Various FBOs, corporate hangers and freight operations have their own backup power. My employer has enough fuel and generator capacity to run for one week, prior to needing refueling.  The A&Ps handle generator maintenance, but there is only one powerplant, so servicing, such as oil changes would happen most likely during daylight hours, by the A&Ps.  I cannot address the other operations.
The FAA FSDO office is on backup power for the office.
One problem with backup power is that it does not assure backup communications.  So in the case of businesses, they may loose connectivity.  Some of the ATC communications have service levels to include communications even with widespread power outages.
In 1992, power was lost at much of the airport for 3 days or more, and some of the gensets were updated after that outage.  My understanding is that even ATC backup power is not standardized for all facilities.
When the generators run out of fuel, they typically shutdown.  Often longer outages are due to weather or natural events.  In those cases, there may not be the ability to get a fuel truck in to deliver generator fuel.
Addendum: Talked with one of the tech who works on a company genset.  He says that they do not use natural gas because the supply might be disturbed with earthquake action.  They all use diesel.  The company genset was trial run on Jet-A but diesel is cheaper, and they have contracts with two suppliers.  If the tankers can get to the airport, the loaders can cut a path to the gensets (in snow).  Gensets vary but generally expect to shutdown every 100 to 500 hours for fluid and filter change.  For larger industrial backup gensets, filing the tanks can be done while running. The genset he oversees has a 10,000 USgal tank plus 500 gal in the genset housing.  Systems for places like Alaska have more complex fuel temperature management to avoid fuel wax precipitation. Larger enterprises, like the regional hospital down the street, use multiple gensets to permit servicing, and to provide higher availability statistics.

Wow, awesome , thanks so much for going out of your way to find that out... it's a shame about the diesel though.. not very environmentally conscious I guess :/

Nearly all generators designed to serve as a backup power source in a safety critical environment (Hospitals, Air Traffic etc) will be designed to run 24/7 "indefinitely" with hot refuelling.
Obviously there will be a real world practical limit to that, but it will be many days if not even weeks potentially depending on the generator.
I suspect there will be huge variation in the type of standby equipment available, pre-loaded fuel and so on depending on the mission. For example, it would be entirely possible to have two generators which can switch over - allowing the other to be serviced and maintained.*
*NB: I don't know if this is an actual "thing", but I'd expect it in certain circumstances, for example, military.

Military, hospitals, yeah - I'm sure they've got backup backup generators. I'd imagine that hospitals, at least, probably have agreements/contracts with local equipment rental places to get generators onsite quickly should the need arise.

@FreeMan Yep, I actually saw a TV show here in the UK that had a backup generator being given a police escort. The hospital had power etc, but it was still given priority due to a lack of redundancy.

@FreeMan, the local hospital, closest to the airport, has six multi-megawatt generators which provide basic power to the hospital, and full power to selected parts of the hospitals.  They test the gensets daily, and replace the units about every six years.  Buying one of those gensets is a sweet acquisition.  The gensets are configured so there can always be one or more offline for service.

If anyone is truly interested, the UK AIP textual data for an airport gives the time in seconds to switchover to a backup power supply. I think the quickest I've seen has been "Less than 1 second". I'm sure this data is also available in every other country's AIP.

In addition, another backup feature for critical activities is to fed buildings using dual power sources, coming from two grid locations with distribution lines routed through different paths.


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What margin of error should one reasonably allow regarding aircraft performance?
This question generated a lot of discussion around amateur pilots often making the mistake of calculating aircraft performance based on perfect conditions and not allowing for a 'safety factor' (i.e. they flew with the maximum possible payload and the passengers had not been honest or accurate about their weight).
The issue, as one commentator stated is that

That’s fine assuming EVERYTHING works out just like the book ie no errors in calculating performance, aircraft and engine in peak condition, field atmospherics, perfect short field takeoff technique, etc.

So, what would be a more sensible approach to calculating aircraft performance and what margin for error should be allowed? This applies to all calculations, payload, runway length, (passenger weight!), airspeed etc. Instinctively I would guess 10% would be fine, but I don't know what I'm talking about :)

Aircraft POH and AFM utilize engineering data obtained from test flights, conducted by highly experienced test pilots who have a goal of presenting the best possible data for an aircraft.  Performance data is used to sell airplanes, long before the owner is working the numbers for his or her operations.  The subject aircraft have been primped, and the engines are working and in ideal condition.  So, if one flies with the same skill, and a finely tuned aircraft, with a ideally running engine, and can repeat a short field take off again and again, until their technique is highly polished, then perhaps one might consider using the book figure.
That doesn't often happen.  For most of us, the aircraft we fly have bug splat on the leading edge, tires that are not perfectly balanced, and other imperfections.  Furthermore, for the weekend flyer, and even for a research test pilot, all operations are not conducted with the degree of refinement which is done during the gathering of data for performance publication.
So given all of that, what are the margins?
I have not seen large scale studies, but I have had several hundred students, and several score of flight instructors who I have taught and prepared. To my knowledge none of them have had any serious accidents, and I have never scratched paint on an aircraft.  So here are my guidelines:
Range in VMC conditions, non-sparse areas 30%
Range in IMC, or night, or over sparsely populated areas 50%
Reduce margins by 10% for every 500 hours of operation in those conditions, down to 10% and 20% respectively.
For operations like take off from short fields, add 50%.  Reduce the margin by 10% for every 20 similar operation over a one month period, which you can verify book performance has been achieved. (Note this seldom happens, because we are seldom watching closely.) Maintain a minimum margin of 10%
Why 10% margins? Well, the windsock may change during your takeoff/landing, the tires might be a little under inflated. There might be bug splat on your leading edge and the airfilter on the engine may have a little dirt on it.  There is always something which is not perfect. So keep a margin.
Determine go/no-go points for TO and LNG.  Do the same for fuel burns on XC operations. If you are going to eat into your predetermined margin, divert.  Chances are the flight that is causing you to eat into your margins may be at night, with rime and clear ice, winds higher than forecast, and more turbulence than you are comfortable with. So with things less than perfect you are absolutely justified in being conservative.
If you are getting book figures, usually there is something not exact as the book.  For example, you may be under gross weight measuring climb.  So don't fool yourself.
One thing you should be able to duplicate is cruise performance.  Dip your tanks after every flight and compare the findings with your calculated figures.  If you can't duplicate the book figures, without margin, then something is wrong.  Climb performance is a bit harder to achieve the precise figures in the book. Even if you can duplicate fuel burn rates, keep a margin.
Making copies of the performance data, and marking the copies with your achieved results will help you recognize where you and your plane are performing.  Having friends spot you on takeoff and landings, perhaps when you are practicing specialty landings, and recording that data is also helpful to assess how you are doing.  Don't forget to record and factor in things like changes in gross weight, winds and even how wet and long the grass is.  They all impact performance.
In my own plane, I have dip sticks which I have calibrated for fuel level, I have a light weight digital bathroom scale, etc. as tools for conducting a flight, with verifiable performance.
In the professional world, I have had to optimize payloads with aircraft to get acceptable performance for low level survey operations. Repeating tests, with supplemental metrics (eg radar altimeter data) and then developing SOPs is something I have spent allot of time doing. All of us can work to refine our procedures and practices to enhance the safety of our operations, without imposing extreme and unjustified margins.
Over the years I have lost too many colleagues and friends to aviation accidents. Retrospectively, every one of them has made one or more judgment errors. Why cut it close, when a little more margin means you may fly again another day?

In addition to @mongo's excellent answer,
you should fly with a margin you (as the pilot in command) feel comfortable with and that falls within the operational performance numbers of the aircraft
Every pilot should develop a set of personal minimums beyond what the FAR's, POH, AFM and other documents say. Generally the more you fly, the more you hone your skills, and the more you understand about the aircraft the lower those minimums get. The minimums may even vary by flight type, cross country, with or with out passengers, local flight etc. For example if its looking like its going to be a bumpy day I may reconsider taking a new passenger up. Or if you trained at a big field with two runways and are not that comfortable with cross wind landings you may way to reconsider that approach into a 2500 ft strip with a 15kt direct cross wind even if its within aircraft limits.
The best way I have found to do this is to fly with an instructor in conditions they fell comfortable with but you may not yet be comfortable with. This will help to get you into a place where you can grow in a safe environment.


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Can I rent a Cessna for a week with my GF with a PPL?
I want to do a 45 hour course to obtain a PPL. The course only includes 10 solo hours but states that it is enough to hire light aircraft.
So could I rent a Cessna after this and take a passenger?

What makes you doubt that with a PPL you can hire an aircraft?

It might help to tell us which country you're in. Apart from the regulations, there may be country-specific requirements or just common practices (e.g. for insurance, or minimum rental times) that affect how easy it is practically - not just legally - to rent an aircraft.

@Pondlife OP has indicated in LAPL vs PPL - Which is more suitable? that "training will take place in the UK" and that the plan is to move to France after getting a pilot's license.

Most people do not take 45 hours to get a PPL, the national average is closer to 70. Do not fall for the "get your license in 45 hours" gimicks. They will give you 45 hours of instruction (and you will probably need more), you also then need to book the examiner and pay for that. 45 hours is difficult to do in short periods of time as well, for example I got my license in 47 hours, way below national average, and it took me 7 months (weather/work/instructor availability/aircraft availability/etc).
So theoretically yes, you can, if you are renting from the same place that you took your training. If not, then you will probably have to pass a check-out which will include about half an hour of ground and an hour or so of air with the company renting the aircraft. You may also not be allowed to rent overnight unless you have X number of hours, again this is up to the rental company.
You also need to have insurance which meets the rental company's requirements. Some rental companies won't rent aircraft overnight, so you need to check that, and if they rent for longer periods of time you will end up paying extra even while the aircraft sits on the ground.
For example, a local company will rent one of the 172's for up to 4 days. The regular rental rate is \$125/hr and overnights are charged $375 for each day.

Thanks Ron, I will have to take the extra costs into account if it can take up to 70 hours. Cheers

@Cloud It can take longer than that, and potentially much longer. If the average is around 70 hours, then a not-insignificant fraction of all student pilots will need more than 70 hours to get to the point where they are able to pass a checkride. (If the 70 hours was the median, then by definition half of all student pilots would need more flight time.) Also add to this the time commitment for learning the theory, and exams, which, while not billed per hour the way flight time is, still represents a time (and to some extent financial) commitment.

@MichaelKjörling Absolutely.  I only have a couple of hours a week to invest really, was hoping to do it in under a year, but we'll see :)

@Cloud A couple of hours a week probably won't do it, IMO. My theory classes were 3-4 hours once per week, plus homework, and that felt very cramped. Add to this the flight time; taking Ron's as an example, 47 hours over 7 months averages out to 1.5-2 hours per week (and don't forget to account for things like preflight checks, pre- and post-flight briefings, etc., which isn't flight time). Even if you're an absolutely stellar student and have great luck with weather and everything availability (not likely), I really doubt you can expect less than 10 hours per week for half a year.

Absolutely, if you indeed get your PPL.

This is the answer to the question, unlike the other replies which talk about the syllabus and so forth.  Yes, with a PPL the OP can do exactly that.  Sometimes just "yes" is the right answer.

@Ralph J: Except that in this case, it's the wrong answer.  The right answer is "It would be legal to do so.  Whether you actually can depends on who you're renting the airplane from".

@jamesqf  Okay, and "can I rent a Cessna..." should probably be qualified to exclude renting a Cessna Citation, or any other twin Cessna.  And yeah you'd need a checkout from someplace that doesn't know you. And if the weather is terrible, then that's an issue. And, not if the Cessna you want to rent is on floats (unless that was part of your training). And lots of other what-if's.  But the basic question is, if I get a private license, is (this) something that I then can do -- to which the answer is, yes -- that's what a PPL allows you to do.

@Ralph J: The PPL allows you to rent from someone who is willing to rent their airplane.  It does not require the entity with planes to rent them for a week to a low-time pilot.

If you just want to be able to take people for rides, just do an NPPL, roughly equivalent to Sport Pilot in the US or Recreational Pilot in Canada/Aus.  The privileges of that license cover 95% of the flying that private pilots do anyway, which is flying around VFR during the day alone or with one passenger.
Probably less than half the cost. Those licenses are a bit less than what the 35 hour Private Pilot course was like 43 years ago when I learned to fly, which cost me $1100 1975 dollars or about 5 grand today.